Filter



Jan. 4. 1938, w WATSON 2,104,473

FILTER Filed Aug. 20, 1955 FICE-.IL

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ATTORNEY.

Patented Jan. 4, 1938 UNITED STATES PATENT OFFICE Oliver United FiltersIncorporated, San Francisco, Calif., a corporation of Nevada ApplicationAugust 2,0, 1935, Serial No. 37,003

3 Claims.

This invention relates in general to filters, and particularly to alocking strip for locking the filter medium of a filter to its frame orsupport, such as the division strip of a rotary drum filter.

The object of the invention is the provision of a zig-zag or corrugatedresilient metal locking strip by means of which the filter medium of thefilter may be detachably secured or locked Within a channel formed inthe frame of a filter or in the division strip of a rotary drum filter.

The invention possesses other advantageous features, some of which withthe foregoing, will be set forth at length in the following descriptionwhere that form of the invention which has been selected forillustration in the drawing accompanying and forming a part of thepresent specification is outlined in full. In said drawing, one form ofthe invention is shown, but it is to be understood that it is notlimited to such form, since the invention as set forth in the claims maybe embodied in a, plurality of forms.

Referring to the drawing:

Figure 1 is a side elevation of a zig-zag locking strip embodying theobjects of my invention.

Figure 2 is a side elevation of a modified form of zig-zag lockingstrip.

Figures 3a to 3e inclusive show five different cross sections in whichthe zig-zag strips shown in Figures 1 and 2 may be made.

Figure 4 is a cross section takenv through the division strip of arotary drum filter, and showing one application of my invention.

Figure 5 is a partial cross section of the frame of a leaf filtershowing another application of my invention.

The zig-zag strip shown in Figure 1 may be considered as defined by anumber of consecutive oppositely pitched portions I and 2 whosejunctions form protrusion or knobs 3 and 4.

The modified zig-zag locking strip shown in Figure 2 is formed by anumber of aligned inter- -rupted straight-portions 5 joined by means ofprotrusions or knobs 6.

Either form of locking strip may be made of any desired cross-sectionsuch as, for example. illustrated in Figures 3a and 3e inclusive.

In Figure 4 the locking strip of the form illustrated in Figure 1 isshown in conjunction with a division strip 'I such asis used on a rotarydrum filter. The division strip 1 is provided with an undercut ortrapezoidal channel 8 within which the filter medium 9 is locked by theaction of the knobs 3 and 4 of the locking strip. Although the lockingstrip as shown in Figure 4 is of general (Cl. 21o-195) trapezoidalcross-section to conform to the trapezoidal channel in the divisionstrip it has been found that other cross-sections will serve equallywell.

In Figure 5, the locking strip of theform illustrated in Figure 2 hasbeen shown as applied to a circular filter leaf comprising a framemember Il provided on its inner periphery with a channel l2 foraccommodating the usual drainage member and supporting screens i3 and oneither side with opposed undercut channels I4 in which the filter mediumI5 is locked by the action of the locking strip. It should beparticularly noted that the interrupted straight portions 5 of thelocking strip faceinwardly and form extended flat bearings which clampthe filter medium l5 against the inner walls of the channel i4. Thisfeature is of considerable importance for it has been found that if thefilter cloth is stretched too tightly over the frame the point contactsof the knobs 3, 4 and 6 have a tendency to rupture the filter mediumwhereasl the extended surface Contacts of the straight portions do not.

The locking strips shown in Figures 1 and 2 provide means whereby afilter medium may be positively and detachably secured within a channelformed in a supporting frame or member at predetermined spaced intervalsand may be used in their generally straight form as shown in connectionwith Figure 4 or curved as shown in connection with Figure 5.

The locking strip is inserted into its channel by first forcing one endinto the channel and then progressively forcing the remainder intoposition. The reverse procedure is followed in disengaging the strip.

I claim:

1. In a filter: a base member; formed in said base member; a section offilter medium disposed within said channel; and a zigzag locking stripresiliently engaged between the walls of said channel and said filtermedium.

2. In a filter: a base member having a channel therein; a fabric liningsaid channel and a zigzag locking strip resiliently engaged within saidchannel and contacting said fabric at spaced intervals.

3. In a filter: a base member having a channel and a resilient lockingstrip formed of extended interrupted flat surfaces joined by outwardlyextending knobs resiliently engaged within said channel.

LLOYD W. WATSON.

a Channel

